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Lasers activate killer instincts in mice.

Scientists have discovered a switch that activatesin mice, predatory instincts. When some parts of the rodent's brain are stimulated with light, mice demonstrate a wide range of hunting skills. Predatory behavior, all this “grabbing” and “biting”, which we know and study well, leaves behind a riddle: it is not clear which brain circuits are involved in it.

Previous studies have shown thatthe central amygdala, the almond-shaped region of the brain involved in the production of emotions, including fear, was activated when rats were hunted. Scientists wanted to find out if the amygdala can control hunting behavior on its own - and a study published in Cell on January 12 says that it can.

To activate the central tonsil in mice Ivande Araoujo, a neuroscientist at Yale University in New Haven, Connecticut, and his colleagues used a technique called optogenetics. First, they infected the mice with a virus that made the neurons of the brain sensitive to blue light. The researchers then used a tiny optical fiber to illuminate the amygdala with a blue laser. This prompted the animals to open their jaws and strain their neck muscles. This behavior did not appear when scientists stimulated other parts of the brain.

When the laser was turned on, the mice hunted for all thathad them in the way, from edible crickets to inedible bottle caps. The researchers observed exactly the same activity when they activated the amygdala with the help of chemogenetics, a similar method of stimulating neurons with molecules rather than light. The behavior of the hunter and feeding appeared even when there was nothing to hunt. When the mice were in empty cages during the activation of their tonsils, they stopped doing what they were doing, positioning their forelimbs as if they were holding food and moving their mouth as if chewing.

Food or friends

All this does not mean that researchersdiscovered a neural circuit of insatiable, bloodthirsty mice, says de Araoujo. “The first thing we thought about was: perhaps this is only generalized aggression. Or we could make mice very hungry. ”

Therefore, the team decided to check it out. Although light-stimulated mice hunted more than intact, both groups ate the same amount. And laser-activated mice could still draw the line between a friend and food. “When they were with a different mouse, they behaved more curiously, but there were no attacks,” says de Araoujo. Therefore, scientists finally convinced that the experiments launched predation, and not hunger or aggression.

This is important becausepredation is a complex behavior, says Kay Thai, a neuroscientist at the Massachusetts Institute of Technology in Cambridge. “This is not only physiological, it is hunting, biting, letting go and eating. These motor sequences require a lot of information, so it is unusual that such complex behavior can be triggered with such rough manipulation. ”

open the door

Once upon a time scientists believed that the central roleamygdala behavior was limited by fear. However, now research has shown that this area of ​​the brain is also involved in a number of complex behaviors, such as courtship. Ty believes that predation can be one of the examples of behavior that lies on the amygdala.

Since the central tonsil is involved in thedifferent behavior, she says, further research is to identify the exact neural circuits involved in the hunt. "The central amygdala was associated with flight and flight — but that is another thing." The hunting animal is looking for something as a reward, she explains.

Ty wants to know how strongly they intersect.schemes that control these two behaviors. She believes that the amygdala can act as a "gate", holding back many programs that are constantly running in the background of the brain. If so, then de Araoujo and his colleagues may have opened the door from which the predator begins.